Concrete structures are commonly used for buildings, parking garages and the like. Over time, cracks can develop within concrete structures. If such cracks are left unrepaired, the cracks can result in failure of the structure. This is a particular problem for parking garages wherein large loads from vehicles daily travel over the concrete surface. To prevent the failure of the concrete structure without having to replace the entire concrete structure, the damaged concrete structure is often repaired by cutting the damaged section away from a preexisting concrete section, and then pouring new concrete into the cutout portion. However, new concrete does not always bond perfectly with the preexisting concrete, thus resulting in the propagation of cracks in the joint between the old and new concrete.
Other methods have been used to repair damaged concrete structures and to maintain the mechanical connection between the new concrete section and a preexisting concrete section. One prior art repair method involves first removing the damaged concrete and then drilling holes in the preexisting concrete using a rotary impact hammer drill. Thereafter, an adhesive is placed into the holes, and reinforcing bars are inserted such that the bars extend beyond the outer wall of the preexisting concrete and are generally perpendicular to the joint between the preexisting concrete section and the gap defining the area where the new concrete is to be poured. The new concrete is then poured adjacently to the preexisting concrete such that the ends of the reinforcing bars extend into the new concrete and bond with the new concrete when the new concrete cures. As a result, when the new concrete cures, it will be joined to the preexisting concrete via the reinforcing bars. When attaching external fixtures to preexisting concrete sections, holes are commonly drilled using a standard rotary drill, and the anchors are either bonded or friction-fitted within the drilled holes. The external fixtures are then mounted onto the anchors.
Several disadvantages are associated with these past methods of repair and attachment of newly poured concrete. For instance, the drilling of multiple holes into the existing concrete is a slow and labor intensive process. Additionally, the vibrations associated with the drilling of the holes can cause an entire section of concrete to fail. Moreover, once a hole is drilled, it must be subsequently cleaned of dust and concrete particles in order to permit the adhesive to properly bond to the concrete. Furthermore, cracks can form over time in the joint between the new concrete section and the preexisting concrete. As such, when moisture seeps down these cracks, the metallic reinforcing bars will rust, corrode, and subsequently fail, thereby necessitating further repair of the concrete section. Also, a phenomenon known in the industry as “burping” may occur, whereby air pockets become trapped within the hole once the reinforcing bar is installed, thereby preventing at least a portion of the adhesive from bonding with the reinforcing bar. Such defective bonding can lead to premature failure of the reinforced joint.
The repair of concrete structures such as a parking garage structure, a concrete driveway or the like that is disposed above T-shaped concrete beams can be problematic. The concrete structures are typically joined together by metal clips. As cracks form in the concrete structures, moisture seeps into the concrete supports and corrodes the metal clips. Such metal clip corrosion ultimately causes the metal clip to fail, which can result in the collapsing of a concrete slab within the parking garage. One prior art method to repair this type of damage involves welding or bolting a supplemental joining apparatus to both supports, thereby retaining them together. This method is expensive and labor intensive. Additionally, the repair is aesthetically unappealing. Another prior art method to repair this type of damage involves cutting through the concrete to access and replace the failed metal clip. Again, this process is labor intensive and expensive.
Another prior art method to repair concrete structures disposed above T-shaped concrete beams is disclosed in U.S. Pat. No. 6,312,541, which is incorporated herein by reference. The '541 patent discloses the use of a half-moon shaped molded composite insert that is inserted into a cut slot in the concrete slab. The slot is cut generally perpendicular to the T-shaped concrete beams and across the gap between two concrete structures. An epoxy material is used to secure the composite insert in the cut slot. The composite insert includes a plurality of cavities that facilitate in the bonding of the composite insert within the cut slot in the concrete slab. Although the molded composite insert is an improvement over prior art methods to repair damaged concrete, there remains a continued need to improve the strength and durability of the repaired concrete.